1. Field of the Invention
The invention relates to the field of propulsion power units mounted on the fuselage of an aircraft and, in particular, to the fairing devices that envelop gas turbine engines.
2. Description of the Related Art
A propulsion power unit generally comprises a gas turbine engine, a nacelle surrounding the engine, and a nacelle support structure. The nacelle comprises, in the direction in which the gases flow, an air intake structure and at least one fairing device.
In the case of small airplanes, the propulsion power units are generally mounted at the rear of the fuselage of an aircraft, toward the top. In such instances, the support structure, also known as a pylon, is fixed by a first end to the nacelle. The second end of the pylon is fixed from a rear location on the aircraft fuselage.
The fairing device of the nacelle often comprises two opening cowls, an upper cowl and a lower cowl, as described in U.S. Pat. No. 4,585,189. These two opening cowls are mounted on the pylon in such a way that they can pivot about a longitudinal axis of articulation parallel to the engine axis via a pivot system situated where the pylon meets the nacelle.
However, given the location of the pivot system, the cowls do not encompass the volume formed by the pylon itself.
Now, provision is often made for equipment, such as air/air heat exchangers and regulating valves, to be installed inside the pylon. Thus, access to the interior of this pylon is needed so that maintenance can be carried out on this equipment. To provide this access, one technology involves positioning removable hatches on the surface of the pylon in line with where the equipment is situated. These hatches are generally produced using riveted panels screwed to the pylon. However, this technology means that it takes a great deal of time to access the equipment located inside the pylon.
Another technology involves positioning additional cowls for the pylon, which can pivot about a lateral axis of articulation perpendicular to the engine axis via a pivot system, situated at the boundary between the region housing the equipment and the region that contains no equipment. This technology makes maintenance easier by reducing the time taken to gain access, but does have the disadvantage of being more cumbersome and complicated to implement.